title: Highly chemoselective reductive amination of carbonyl compounds promoted by InCl3/Et3SiH/MeOH system.
abstract: A new strategy has been developed for reductive amination of aldehydes and ketones with the InCl3/Et3SiH/MeOH system, which is a nontoxic system with highly chemoselective and nonwater sensitive properties. The methodology can be applied to a variety of cyclic, acyclic, aromatic, and aliphatic amines. Functionalities including ester, hydroxyl, carboxylic acid, and olefin are found to be stable under our conditions. The reaction shows a first-order kinetics profile with respect to both InCl3 and Et3SiH. Spectroscopic techniques such as NMR and ESI-MS have been employed to probe the active and resulting species arising from InCl3 and Et3SiH in MeOH, which are important in deriving a mechanistic proposal. In the ESI-MS studies, we have first discovered the existence of stable methanol-coordinated indium(III) species which are presumably responsible for the gentle generation of indium hydride at room temperature. The solvent attribution was crucial in tuning the reactivity of [In-H] species, leading to the establishment of mild reaction conditions. The system is superior in flexible tuning of hydride reactivity, resulting in the system being highly chemoselective.
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, People's republic of China.
authors.forename: On-Yi
authors.initials: OY
authors.lastname: Lee
authors.forename: Ka-Lun
authors.initials: KL
authors.lastname: Law
authors.forename: Chun-Yu
authors.initials: CY
authors.lastname: Ho
authors.forename: Dan
authors.initials: D
authors.lastname: Yang